Improvement in furnaces for roasting and treating ores



rra v'rn'rns CHARLES STETEFELDT, OF AUSTIN, NEVADA.

IMPROVEMENT IN FURNACES FOR ROASTING AND TREATING OBES.

Specification forming part of Letters Patent No. 72,931, dated December 31, 1867.

To all whom it may concern:

Be it known that I, CHARLES STETEFELDT of Austin, county of Lander, State of Nevada, have invented certain new and useful Improvements in Furnaces for Chloridizing Silver Orcs; and I do hereby declare the following description and accompanying drawings are sufficient to enable any person skilled in the art or science to which it most nearly appertains to make and use my said invention or improvements without further invention or experiment.

My invention is intended to provide an improved furnace for chloridizing silverores preparatory to amalgamation.. v

This furnace is constructed with a shaft, the fall of the ore through which is retarded by the upward motion of the heated air and chloridizing-gases, combinedwith are-place opening into a canal below the flue. The flame or heated air passing up the shaft heats the particles of the falling ore, retarding their fall, and effecting their perfect desulphurization and chlorination, which latter is, to a great extent, achieved by the chlorine, hydrochloric acid, and volatile chlorides whichcontinue to emanate from the roasted ore accumulated in the bottom of the shaft. A ue at the top of the shaft allows the gases to pass into a series of dust-chambers connected with a chimney.

As the ore has to be pulverized very fme preparatory to amalgamation or other processes of extraction, a part of the charge will necessarily be carried by the draft directly through the flue into the dust-chambers, and is, consequently, either entirely raw or at least imperfectly chloridized.

To effect a perfect chlorination of this part of the ore, a small nre-place builtl at the up-.

per end of the shaft is connected with the flue, and as the ore is so very fine and in an atmosphere of chloridizing-gases, its chlorination is completed in a moment in passing the ilame in the iiue.

To more fully illustrate and describe my furnace, reference is had to the accompanying drawings and letters marked thereon, of which- Figure l is a section taken through P P; Fig. 2, a section through M M; Fig. 3, a section through H H Fig. 4, a section through 0 O.

I' `B represents the perpendicular shaftv of the of the shaft, from which the flame and gasespass up the shaft B, and through the flue D and canal H into the dust-chambers I I. J is the small fire-place at the upper part of the shaft, opening below the flue D into the canal H', which may be constructed inclined or level, where the ore is chloridized which is too iine and light to fall down the shaft B. In order to heat already the gases in the flue D, the arch of the ire-place lJ is formed by an iron plate, K. l

In the lower part L of the shaft B the roasted ore accumulates, andis discharged through the door M.

The operation of my furnace is as follows, to Wit: Fire is made in the fire-places C and J, and as soon as the inner walls of the shaft are red-hot the rollers are put in motion, and the ore is fed in continuous streams through the 4slits a a a in the iron plate E. To accomplish an intimate mixture `of the ore and salt, it is best to crush them together in a dry crushing-battery. The only attention which the furnace requires is the keeping up of a regular roasting heat. The roasted ore is allowed to accumulate in the bottom of the shaft nearly upto the nre-bridge of the lire-place (l. This is very important, as a great amount of chlorine, hydrochloric acid, and volatile c1110- rides emanates from the charge, and acts upon the fallingore in the shaft. If the ore accumulates toomuch, a part is discharged through the door M', but so as to allow no cold air to enter the shaft. The ore which is roasted in the canal H bythe heat from the fire-place J, and deposited in the dust-chambers I I, is taken out from there occasionally.

A furnace with a shaft twenty-live feet high and three feet square will roast, in twenty-four hours, from eight to twelve tons of ore, and burn from two to two and one-half cords of wood.

The expense of roasting will be rediiced by this new process more than one-half of the present rates 'in reverberatory furnaces.

I do not claim treating ore by letting it fall in fine powder through a shaft with the productsof combustion, so as to roast and deopening into the canal H andi below the flue sulphurize the same, as described in the pat- D, substantially as described, and for the purent of Whelpley and Storer, dated January 12, poses set forth. u

1864; but In witness whereof I have hereunto set my What I do claim, and desire to secure by hand and afxed my seal.

Letters Patent isy A furnace constructed with a shaft, B, the CHARLES STETEFELDT [L' S'] fall of the ore through which is retarded by Witnesses: the upward motion of the heated air and chlo- GEORGE T. STODDER, rdizing-gases, combined with a fire-place, J, A. M. BERRY. 

